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1 Billion Years of PNW Geology in 10 (text) Slides or Less
Important ProcessesTectonicsVolcanismErosion/DepositionGlaciationDiscrete Disturbances
PNW Timeline A4.5 BYA Earth Formed~ 4.4 – 4. 2 BY Oldest Rocks (U in Zircon
degradation to lead Pb)2.7 BYA basement Rocks in MT, ID1.5 BYA Purcell Belt Basin~44o MYA Pangaea Starts to Assemble (Silurian
Epoch of Paleozoic Era)Coastline ~ Idaho border. 30,000 feet of marine
sediment accumulates~ 400 mya Blue Mt. Terrane forming in tropical Pacific
(limestone)(made of 5+ terranes)Klamath Arc Collides, Antler Highlands (proto-Sierras)Intermontane, insular terranes develop in S.W. Pacific
Metamorphosed to Become
Geologic Time Scale
Eon Era PeriodAge at Base*
(start)
Phanerozoic
CenozoicQuaternary 1.6 Ma
Tertiary 65 Ma
Mesozoic
Cretaceous 140 Ma
Jurassic 205 Ma
Triassic 250 Ma
Paleozoic
Permian 290 Ma
Carboniferous
355 Ma
Devonian 410 Ma
Silurian 438 Ma
Ordovician 510 Ma
Cambrian 540 Ma
Precambrian
Proterozoic
Vendian 680 Ma
2500 Ma
Archean 3960 Ma
Hadean 4550 Ma
Cenozoic Era (New Life)Two periods of Old
Version:Quaternary Period 1.6
mya Holocene Pleistocene
Tertiary Period 65 mya Pliocene Paleocene or Miocene
Two periods of New Version:
Neogene Period 23 myaHolocene Epoch ~15,000
to presentPleistocene Epoch 1.8
myaPliocene Epoch 5.3 mya Miocene Epoch 23 mya
Paleogene PeriodOligocene Epoch 33 myaEocene Epoch 55 myaPaleocene Epoch 65 mya
Cenozoic Era (New Life)Two periods of Old
Version:Quaternary Period 1.6
mya Holocene Pleistocene
Tertiary Period 65 mya Pliocene Paleocene or Miocene
Two periods of New Version:
Neogene Period 23 myaHolocene Epoch ~15,000
to presentPleistocene Epoch 1.8
myaPliocene Epoch 5.3 mya Miocene Epoch 23 mya
Paleogene PeriodOligocene Epoch 33 myaEocene Epoch 55 myaPaleocene Epoch 65 mya
PNW Timeline B~245 MYA Pangaea Assembled (Permian Epoch of Paleozoic
Era) Large, warm seas Several (lost) sub/mini continents/islands in Pacific
Permian – Triassic Extinction Event ~251 mya Larger extinction event than K-T Impacts, Volcanism, Methane Hydrates from sea floor (?)
~200 MYA Pangaea Starts to Break up (Triassic Epoch of Mesozoic Era) Forms Laurasia (N) and Gondwanaland (S) Marine Seas changing to smaller back arc basins with volcanic
chains~ 140 mya Laurasia Breaks Up (Jurassic Epoch of Mesozoic Era)
Ocean rift starts to form Atlantic Ocean N. America moves across Pacific and Farallon Plates
(subduction) Intermontane Superterrane Collides with N. America
From Orr and Orr, 2005, p. 6
From Orr and Orr, 2005, p. 2
From Orr and Orr, 2005, p. 5
PNW Timeline C~ 144 mya – 65 mya Cretaceous Epoch of
Mesozoic EraBatholith intrusions throughout PNWN. Cascade Terrane Collides (started 500 mya)Insular and Blue Mt. Terranes CollideIdaho Batholith late CretaceousLarge Seas cover PNW
BAM! Huge Meteor hits Earth, Extinction of Dinosaurs (K-T Extinction Event)Location: Yucatan Peninsula (others? SL-9)Deccan Traps alternative Hypothesis?
Farallon Plate subducts with less angle, faster
Several km in Diameter; ~ hundreds of nuclear weaponshttp://en.wikipedia.org/wiki/Image:Impact_event.jpg
http://en.wikipedia.org/wiki/Image:Chicxulub_radar_topography.jpg
http://upload.wikimedia.org/wikipedia/commons/5/57/K-T_boundary.jpg
Timeline D~58 mya Coast Range Mt. Volcanism (ocean)Pacific Rim, Crescent, Siletz Terranes “arrive”Farallon Plate subducts steeper, slower~40 mya W. Cascade Volcanism Begins (old
Cascades)~ 36 mya Kula Plate completely subductedBlue Mts. Rotate/arch upwardJohn Day Volcanism smothers fossilsWet, Warm Tropical Environment changes to dry
temperate~20 – 5 mya Coast Range (not BC) and Olympics
uplift
Cenozoic Era (New Life)Two periods of New Version:Neogene Period 23 mya
Holocene Epoch ~15,000 to presentPleistocene Epoch 1.8 myaPliocene Epoch 5.3 mya Miocene Epoch 23 mya
Paleogene PeriodOligocene Epoch 33 myaEocene Epoch 55 myaPaleocene Epoch 65 mya
From Alt and Hyndman, 1995, p. 171
Timeline E~17 -- 14 mya Flood Basalts in WA and OR
(Steens Basalt)17 – 15 mya Basin and Range (fault-blocks from
spreading)~13 mya Snake River Plain Hotspot (at
Yellowstone now)~5.3 mya First High Cascades eruptionsCascade Rainshadow “renewed”
Dry, cooler inland Climate Continental ClimateTemperate Climate to west Maritime Climate
http://en.wikipedia.org/wiki/Image:3-Devils-grade-Moses-Coulee-Cattle-Feed-Lot-PB110016.JPG
http://en.wikipedia.org/wiki/Image:Horst_graben.jpg
http://en.wikipedia.org/wiki/Image:HotspotsSRP.jpg
Timeline F~2 – 3 mya Puget Lowlands and Willamette valley
forming – rift faulting?Long dry spellYellowstone (2.2 mya and 640,000 ya) eruptionTHEN Pleistocene 1.8 mya
100,000 years ago first glaciationLong series of glacial phases (colder –
wetter/warmer – drier)Lake Missoula (+/- 100s?)and Bonneville (1) floods10,000 years ago ice age endsE. Snake River basaltsMazama (5,677 (± 150) ya) eruption
http://en.wikipedia.org/wiki/Image:Northern_icesheet_hg.png
http://www.nwcreation.net/articles/missoulaflood.htm
http://www.greaterthings.com/News/daily/2005/09/06/6600916_Bush_behind_Katrina/Lake-Bonneville-and-Utah.jpg
http://pubs.usgs.gov/fs/2002/fs092-02/
http://volcano.und.edu/vwdocs/volc_images/north_america/crater_lake.html
http://en.wikipedia.org/wiki/Image:HotspotsSRP.jpg
http://www.exodus2006.com/supervol.html
http://en.wikipedia.org/wiki/Image:Yellowstone_Caldera_map2.jpg
Puget Sound At Glacial Maxima Seattle under up to 1000m of
iceLakes formed at edges of glaciers (Russell,
Nisqually, Bretz, many others)Some drained into Chehalis River (underutilized
drainage)Water changed from fresh to brine/salt
(extinction)As Glaciers receded, glacial formations
Mima MoundsClays and TillMorraines
From Orr and Orr, 2005, p. 17
From Orr and Orr, 2005, p. 17
http://en.wikipedia.org/wiki/Image:Puget_Sound_from_Space_Needle_High_Rex.jpg
http://en.wikipedia.org/wiki/Image:Cascade_Range-related_plate_tectonics.svg
http://en.wikipedia.org/wiki/Image:Cascade_eruptions_in_the_last_4000_years.png
SourcesOrr, W.N. and E.L. Orr. 2006. Geology of the Pacific
Northwest. Waveland Press, Long Grove, IL.Alt, D. and D.W. Hyndman. 1995. Northwest Exposures.
Mountain Press Publishing Company, Missoula, MT. Check out this website to reconstruct plate tectonic movements
on your own: http://www.odsn.de/odsn/services/paleomap/paleomap.html
Check out KT Event: http://en.wikipedia.org/wiki/Cretaceous_extinction
Also look at QuickTime movie of Puget Sound Glaciation at http://exhibits.pacsci.org/puget_sound/graphics/ps_glaciationsm.mov
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